POPs – The Latest
POPs – Climate change Interactions
Climate change will affect contamination of the Arctic by hazardous chemicals in various ways. A new assessment of the implications of climate change for Arctic contamination by persistent organic pollutants (POPs) is being produced during 2019/2020.
POPs are chemicals that are characterized by their properties of persistence (which gives potential for long-range transport), bioaccumulation and toxicity.
Possible influences of climate change on POPs
Past AMAP work has described the status of Arctic POPs contamination, including changes in levels of POPs observed in Arctic biota and abiotic media over time. Increasingly, the question of the role of climate change in determining these trends has arisen.
Climate change can affect POPs exposures in animals and humans throuhg both physio-chemical processes and ecosystem-related changes.
Climate change can affect persistence and long-range transport. Most POPs emissions and releases are associated with industrial and agricultural sources far from the Arctic. POPs therefore reach the Arctic as a result of transport in the atmosphere and oceans, and by northward flowing rivers. POPs are only slowly degraded in the environment; their environmental persistence allows them to be transported over long distances. Many POPs are deposited from the atmosphere to the Earth surface but then have the ability to be re-emitted to the atmosphere under environmental conditions that favour this process. This cycle of deposition and re-emission gives rise to a process known as ‘global fractionation’ that promotes transport of these chemicals to cold polar regions.
Under changing environmental conditions the rates of degradation of environmental contaminants can change; melting of ice and snow, thawing of permafrost and warmer temperatures may enhance the release of chemicals that have accumulated in soils, glaciers and surface ocean waters. Loss of sea ice makes contaminant exchange between the atmosphere and oceans easier.
Changes in wind patterns, ocean currents, precipitation and runoff will all affect contaminant pathways and connections between source and receptor regions.
Bioaccumulation and toxicity: POPs can bioaccumulate in Arctic food webs and, due to their persistence and tendency to associate with lipids, many biomagnify in food chains. High levels of POPs in species that are high in the food chain (especially in marine food-webs) lead to exposure to these chemicals by certain animals and people that consume these species as part of their subsistence diets. This, together with the toxic properties of many POPs, raises concerns for both human and wildlife health.
Changing climatic conditions in the Arctic are leading to changes in ecosystems. Some species are challenged by the changes that are occurring, such as species that rely on sea ice habitats; others are moving in to areas where conditions are now more hospitable. Changes in species composition, and phrenology (timing of events) is resulting in changes in ecosystem structures. If species start to change their diets this can introduce new steps in biomagnificaiton characteristics that determine POPs levels in animals, potentially increasing or decreasing levels of exposure by several orders of magnitude.
AMAPs work on climate-chemical interactions and its relevance to international processes that aim to reduce global POPs contamination
Arctic contamination by persistent organic pollutants (POPs) and chemicals of emerging Arctic concern (CEAC) has been documented in recent AMAP assessments (2014, 2015) building on earlier assessment work addressing these subjects (1998, 2002, 2009).
In 2002, AMAP produced its first assessment of the influence of global change on contaminant pathways to, within, and from the Arctic. At that time, evidence of climate change impacts on Arctic environments was only just beginning to appear.
This work was expanded in a collaborative work between AMAP and UNEP that resulted in the 2011 report climate change and POPs: predicting the Impacts, which considered possible implications of climate change on POPs at the global scale.
AMAPs work plan for the period 2019-2021 includes a new update assessment of the interaction between Arctic climate change and POPs. Past work evaluated processes by which climate change may influence POPs levels in Arctic environments and biota from a largely hypothetical perspective. In light of the unprecedented change in Arctic snow, water, ice and permafrost conditions that have been documented over recent decades, the new assessment will look for evidence that these processes are actually beginning to occur and influence observed trends in Arctic POPs contaminantion.
The results of the assessment will be communicated to bodies such as the Stockholm Convention and UN ECE Convention on Long-range Transboundary Air Pollution – that examine trends in POPs as part of their work to evaluate the effectiveness of measures introduced to reduce POPs pollution globally.
Understanding the factors (in addition to changes in primary use, releases and emissions) that determine changes in levels of POPs observed in the environment and humans is essential for a valid interpretation of trends and so that valid conclusions can be drawn about the effectives of policy measures.